QTL Mapping Of The Leaf Number Above The Primary Ear And Its Breeding Utilization Evaluation In Maize

Maize(Zea mays L.)is an important crop which serves as food and forage,and it plays an important role in agricultural production and national economic development.Lacking of germplasm resource was the leading problem in the breeding.Therefore,it is necessary to increasing the maize germplasm resources in order to keep up the changing pace of maize breeding.The leaf number above the primary ear(LA)is a major contributing factor to plant architecture in maize.The yield of leafy maize,which has extra LA compared to normal maize,is higher than normal maize in some regions.In order to better utilize maize germplasm resources for maize breeding,it is necessary to further study the heredity of leafy trait.Here,using linkage analysis to mapping leaf number above the primary ear and its relationship with plant height,flowering time and yield in maize.The major results are as follows:1.Using an F2:3 population comprising 190 families derived from a leafy maize line Y915 with 9 LA and a normal maize line Z58 with 4 LA,an association population comprising 437 inbred maize lines,we mapped the quantitative trait loci(QTL)associated with LA,Ten QTL with an additive and dominant effect,two major QTL,qLA3-4 explained the 58.9%phenotypic variance and qLA7-1 explained the 20.3%phenotypic variance,were repeatedly detected and explained a large proportion of the phenotypic variation.Eighteen pairs of interacting QTL in the F2:3 population and seventeen significant SNPs in the association population were detected for LA.2.To investigate the genetic relationship between LA and related traits,correlation analysis and the QTL analysis for related traits were mapped in the F2:3 population and compared with those identified for LA in the same population as described above.Two major QTL overlap regions was detected on chromosome 3 and chromosome 7.Notably,the QTL detected in bin3.09,qLA3-4 were found to have significant effects on the LA,PH,EH,DTT,DTS,DTA,KW and LANA.Two near-isogenic maize lines(NILs)with different LA were developed from a single F6 individual arising from a cross between leafy maize line Y915 and the normal line Y53.To validate the genetic effect of qLA3-4 on LA,PH,EH,DTT,DTS,DTA,KW and LANA observed in the F2.3 population.NIL6L and NIL9L were investigated for LA,PH,EH,DTT,DTS,DTA,KW and LANA.Significant phenotypic differences in LA,PH,EH,DTT,DTS,DTA,KW and LANA were found to exist in the two NILs.These results further suggest that qLA3-4 affects not only LA but also PH,EH,DTT,DTS,DTA,KW and LANA.3.Four maize series(CJJ、RZ373、ZYZ-4 and WN2000),with different hereditary background were used to cross with NIL6L and NIL9L.The general combining ability of NIL9L is higher than that of NIL6L.The most excellent combination(NIL9LxWN2000)shows high yield,moderate growth and moderate height are selected according to the analysis of special combined forces.